Process of producing colored photographs



Sept. 11, 1951 P. RAIBOURN 2,567,401

PROCESS oF PRoDucING COLORED PHOTOGRAPHS Filed April 18, 1947 Britti reel autel Chlo-l deL/@Q red inte ReclLuce St'lx/er cund: olfzs'SoLx/ .Silk/n ralicle below nage red; ingle PrdE green' and cul'vdeh/[079 green. nlcggg Reduce .sL/er and. dssob/c Sib/en halide bellow ragga 1] Ted inw. clqe `Cecu" ian/er grec". ncge clear Egger- Patented Sept. 11, 1951 PROCESS OF PRODUGING- COLORED PHOTOGRAPHS l Paul -Raibourn, Southport, Conn.

Application April '18, 1947, Serial l\10.7`fl2.,460v

8 Claims.

The object of this inventionis lto provide an `economical and relatively simplemethod of producing useful colored photographs from color vseparation negatives in a single layer lemulsion film.

The detailed objects of the invention and the resulting products will be fully apparent from 'the following description ofthe invention.

This invention resides substantially in the steps and series of steps comprisingfthe'processes herein disclosed and the products thereof as Aderlnedin the appended claims.

In the single figure of the drawing, vthere is illustrated diagrammatically in -edge elevation, by way of example, one way lof carrying out'the process herein disclosed.

In accordance with this invention three positive subtractive images are successively printed and developed to color in a single layer of light sensitive material of a color blind (blue sensitive) type. The images of the separation negatives are successively printed and developed at diierent depths in this emulsion bythe'procedure hereinafter described. The emulsion of such a iilm may be of the panchromatlc or equivalent type sensitive either to the entire visible'spectrum -or to a limited portion thereof as wel1,as suggested above, as a color blind-emulsion.

In order to accomplish the vobjects of this inventionthe layer of light sensitive material will jbe of such thickness as to contain three-imaginary depths so to speak, Aof such thickness as to conveniently produce images cfsatisfactory color contrast by the herein disclosed methodswof producing the color images plus an allowance for error in the controlled penetration of solutions, as explained below. Asa more dimensional delinition the emulsion layer will be ofthe orderof thickness of the well known Kodachrome lrn `plus an additional thickness providing itwo Aallow-- ances for error, the nature of which will'appear more fully hereinafter.

In accordance with this invention it will be assumed .that there are available three balanced separation negatives of a scene and .of desired density range such as may be obtainedin a well known manner with so called WrattenA, B and C filters. The image in the red recordnegative (produced by the A filter) is printed with ultraviolet lighton a sensitive film as illustrated in the drawings, that is a commercial color blind silver sensitive emulsion. Theprintingis effected to a sufcient depth to produce a satisfactory depth of color. The printing .light may be an ultra-violet light for the purpose of limiting the depth of penetration of the light'into the remulsion so that substantially the upper thirdthereof is exposed. Those skilledin the art will also lrecognize that such anemulsion can be controlled also as to depth :ofprinting .by dyeing it with a dye complementarylto the colorh of the'printing light;f For example, it could bek dyedwith Auramine in the case of a blue printing light;

The v concentration of the dye will be 'adjusted so as to produce an image in the desired depth forthe ydensity range fin-the lseparation :negatives: The .printing may be done'while the emulsionis still'wet from the dyeing process, but in this case. itl 4must be; printed optically. AsV those skilledin the vartzwill understand, ifk thek iilm was printed while wet the hydrogen ion concentration .mustzfbe carefully determinedzto minimize swellling of the gelatin.

'The latent image vthus formed will be processed. to la cyan` color by fmeans'of direct or coupled development with well known developers. such as are used in .Kodachrome The silver which is deposited with the color is then removed by'reducing it to silver bromide with ,ferricyanide-bromide solution and' removing itl and the-undevelopedsilver bromide to -the ldepth just beyondlthe deepest Ydepthof developed silver with neutral hypo solution which is conf trolled in ,itslpenetration Thisstep caribe carried out..by combining the reducingand bleaching solutions inwhich case :the amount of silver halide .removed is controlled by addingto the solution loading agents known. for the purpose, suchasglucose, sodiumsulphate orglycerin. If the twosolutionsare usedseparately only penetrationof the hyposolution needbe controlled.

The penetration of the solutionin accordance with the above is controlled so that all reduced silveris removed,with the result that the silver halide in the emulsion will be removed to a slightly-greater depth than the silver. This addition depthl represents one of the thickness `allowances for error previously mentioned. Processing the lm to cause this excess penetration is an important feature of this process in that close -controlv ofv penetration depth of the soluytion lis not necessary `where this allowance is provided.

There` nowr remains in :the sensitive yemulsion an' upper rlayer containingk adesired cyan image, a thin clear layer-(the error allowance) anda thicker layer of sensitivesilver-halide emulsion representing approximately two-thirds of the emulsion'depth.

The image` ofthe 'green separation negative the purpose either of the coupling or direct developei` type. The silver image is removed as before by means of ferricyanide and hypo solution, as described above.

There now remains in the emulsion from the emulsion face downwardly:

1. A cyan image 2. A thin clear layer 3. A magenta image 4. A thin clear layer 5. A layer of silver halide emulsion.

Of course, the ferricyanide-bromide and hypo solutions were used as in the first case by controlled penetration in depth to clear the emulsion a very small distance beyond the middle image layer.

The blue record image is printed either by direct contact or optically in the manner and under the conditions set forth for the previous images. It is then developed to yellow with well known coupling or direct developers.'` The silver and remaining halide is then removed-as before by means of ferricyanide-bromide and hypo solutions.

The film now contains color images which will be a close representation of the original if the density matrix of the three subtractive colors formed in the development approximate the following values:

Cyan g1g/ga Yellow The silver im-ages may be colored as desired by well known toning processes in which case the silver images will not be reduced torsilver halide but will remain in each case and only the undeveloped silver halide will be removed.

As is well known, colors of such characteristics are not readily available. The density matrix of a more usual and common set of subtractive colors may be:

Cyan glglt'a Yellow satisfactory representation of the original scene.

Such masks can be recorded and the negatives neutralized and reduced in the original separation negatives. Where many copies are to be made this is the preferable procedure. It is also possible to record such masks automatically in the printing of the positive images, or if desired, to effect the necessary masking by a combination of these procedures.

To produce the masks in the positive printing process the procedure is as follows: In printing with blue light it is inherent that in printing the magenta image through the cyan image printing is effected through a positive which has the density of 0.30 to the blue light. The desired additional mask of 0.30 may be obtained by using a proportional reduction procedure in accordance with well known processes to eliminate '70% of the silver from the cyan image and allow 30% to remain when the magenta image is printed. In a similar manner the yellow image may be properly masked by printing through the cyan and magenta images from which all of the silver has been removed. In this Way a satisfactory color representation may be obtained.

From the above description it will be apparent to those skilled in the art that the subject matter of the invention herein disclosed is capable of being practiced with the aid of variations in the photographic processes indicated above without departing from the novel subject matter herein disclosed. I do not, therefore, desire to be strictly limited to the details included herein for purposes of illustration, but rather by the scope of the claims granted me.

What is claimed is:

1. A method of producing a three-color positive nlm from three-color separation negatives red, green and blue, comprising the steps of printing the red record image in a single silver halide emulsion panchromatic lm to a controlled depth, developing the image thus formed to cyan, reducing the silver in that image to silver halide, dissolving it and the silver halide in the emulsion below the image for a short distance to form a thin clear layer, printing the green record image in the emulsion through the cyan image, developing this second image to magenta, reducing the silver in that image to silver halide, dissolving it and the silver halide in the emulsion below the image for a short distance to form a thin clear layer, printing the blue record image in the emulsion below the magenta image through the cyan and magenta images, developing that image to yellow, reducing the silver of that image to silver halide and dissolving it.

2. In the method of claim l, said panchromatic emulsion being dyed a color complementary to the 'color of the printing light.

3. In the method of claim 1, said panchromatic emulsion being dyed yellow and said printing steps being effected with blue light.

4. In the method of claim 1, the step of proportionally reducing the silver image in the first two layers to form a positive mask for printing the yellow image therethrough.

5. In the method of claim 1, the step of proportionally reducing the silver in the cyan image to provide a positive mask through which the magenta image is printed.

6. A method of producing a multi-color positive film from color separation negatives, comprising printing the images from said negatives successively to succeeding depths in a single silver halide emulsion on a supporting backing to produce superposed image layers, successively developing each image after printing to color and to silver, and removing the silver in each layer immediately after development of each layer tc color and the silver halide to a depth beyond each image layer to provide a clear gelatin layer between each pair of color image layers.

'7. In the process of claim 6, controlling the removal of sliver and silver halide after each development by controlled penetration to form said clear layer adjacent each color image.

8. In the method of claim 6, the removal of the silver image being effected by reducing the silver to a halide and dissolving it and undeveloped silver halide to form a clear layer.

PAUL RAIBOURN.

REFERENCES CITED The following references are of record in the le of this patent:

Number Number UNITED STATES PATENTs Name Date Leventhal Jan. 1, 1929 Lierg May 15, 1934 Burwell July 10, 1934 Mannes et al. Aug. 7, 1934 Mannes et al. Nov. 3, 1936 Mannes et al Nov. 3, 1936 Mannes et al. Apr. 5, 1938 Murray et al May 23, 1939 Weaver Jan. 9, 1940 Bertrand May 7, 1940 Symmes Aug. 7. 1945 FOREIGN PATENTS Country Date Great Britain Aug. 8, 1939 

1. A METHOD OF PRODUCING A THREE-COLOR POSITIVE FILM FROM THREE-COLOR SEPARATION NEGATIVES RED, GREEN AND BLUE, COMPRISING THE STEPS OF PRINTING THE RED RECORD IMAGE IN A SINGLE SILVER HALIDE EMULSION PANCHROMATIC FILM TO A CONTROLLED DEPTH, DEVELOPING THE IMAGE THUS FORMED TO CYAN, REDUCING THE SILVER IN THAT IMAGE TO SILVER HALIDE, DISSOLVING IT AN THE SILVER HALIDE IN THE EMUL-SION BELOW THE IMAGE FOR A SHORT DISTANCE TO FORM A THIN CLEAR LAYER, PRINTING THE GREEN RECORD IMAGE IN THE EMULSION THROUGH THE CYAN IMAGE, DEVELOPING THIS SECOND IMAGE TO MAGENTA, REDUCING THE SILVER IN THAT IMAGE TO SILVER HALIDE, DISSOLVING IT AND THE SILVER HALIDE IN THE EMULSION BELOW THE IMAGE FOR A SHORT DISTANCE TO FORM A THIN CLEAR LAYER, PRINTING THE BLUE RECORD IMAGE IN THE EMULSION BELOW THE MAGENTA IMAGE THROUGH THE CYAN AND MAGENTA IMAGES, DEVELOPING THAT IMAGE TO YELLOW, REDUCING THE SILVER OF THAT IMAGE TO SILVER HALIDE AND DISSOLVING IT. 